From the viewpoint of environmental conservation, current automobiles are required to reduce the emission gas substances such as carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOx) contained in the exhaust gas of automobiles and cylinder fuel injection type internal combustion engines for the purpose of reducing these substances are widely known. The cylinder fuel injection type internal combustion engine directly injects fuel into a combustion chamber of a cylinder with a fuel injection valve, and by reducing the particle diameter of fuel injected from the fuel injection valve, combustion of the injected fuel is promoted to reduce the amount of exhaust gas substances and to improve the engine output and the like.
In order to reduce the particle size of the fuel injected from the fuel injection valve, measures for increasing the pressure of the fuel are necessary, and various technologies of a high-pressure fuel pump for pumping high pressure fuel to the fuel injection valve is proposed.
For example, known is a technique of reducing the driving force of the high-pressure fuel pump by controlling the flow rate of the high pressure fuel supplied in accordance with the fuel injection amount of the fuel injection valve (see, for example, PTL 1). PTL 1 describes two types of electromagnetic valves, namely a normally open type and a normally closed type, as the flow rate control mechanism, but in either case, the volume of the fuel pressurized by the high-pressure fuel pump is adjusted by controlling the timing at which the intake valve closes during the discharge process.
An intake valve of the high-pressure fuel pump is controlled with an electromagnetic valve between the open position and the closed position, and known is a technique in which the current driving the electromagnetic valve is changed in two stages when the intake valve is controlled from the open position to the closed position (see, for example, PTL 2). According to the technique of PTL 2, the operation sound (the impact sound of the intake valve) is suppressed by reducing the current value before the completion of the movement of the intake valve to the closed position with respect to the current at the time of starting energization so as to lower the moving speed of the intake valve.
Furthermore, a technique is known for controlling the amount of fuel fed under high pressure from a high-pressure fuel pump by using the timing of energizing an electromagnetic valve (see, for example, PTL 3). In the technique of PTL 3, when the electromagnetic valve is supplied with electricity during the compression process of the high-pressure fuel pump, the plunger rod moves away from the intake valve, and the intake valve moves to the closed position by the spring force and the fuel pressure. Since the pressure in the pressurizing chamber is high after the intake valve is closed, even when the electromagnetic valve is deenergized and the plunger rod is pressed against the intake valve, the intake valve is held in the closed position. When the piston plunger moves toward the bottom dead center and the pressure in the pressurizing chamber decreases, the plunger rod and the intake valve move in the opening direction.